Earlier quoted context omitted.
So your complaint is the POTUS should've come to the AMA with more time to spend, hunted down "better" questions to answer, and then spent more time thoroughly answering the questions. Someone else's complaint is going to be, why is the POTUS wasting his time and our tax dollars with reddit? Someone else's complaint is going to be that reddit's lucky POTUS gave them any of his time and that reddit was not appropriate…
So your complaint is the POTUS should've come to the AMA with more time to spend, hunted down "better" questions to answer, and then spent more time thoroughly answering the questions. You clearly are not reading the subtext of what (s)he's saying, or you're willfully ignoring it to appear steadfast in your dissent: it has been admitted and acknowledged that the POTUS had a limited amount of time with his interaction…
What exactly do you expect? The POTUS to, simply because he is on reddit, to suddenly say "By the way, I smoked pot, I'm an athiest, I think the RIAA is evil, etc.?"
He is the current President and actively campaigning for re-election, and he stated up front that he had 30 minutes to burn to "personally" answer questions. To expect this AMA to have gone any other way is simply naive. Regardless of what you believe politics are or should be, expecting anything different is neglecting the reality of modern politics.